Potty "trainer"
No, we have not start potty training with Kiharu yet (grandma, we are saving that job for you again this summer at YOUR house ^_^). As many people suggested, younger siblings tend to learn things much faster as they copy the older ones on everything, including bathroom visit...
This afternoon, suddenly Kiharu was pointing to her pants and said she wanted to poop, which normally she would have just quietly done it behind the scene. Yoshi heard it, and said "Kiharu, let's go to bathroom, I will help you." Of course, I followed them right behind (who knows what Yoshi meant by "teaching").
Yoshi pulled out the hidden potty training seat, set it up on the toilet for Kiharu. She was very willing to try it. One wanted to teach, and one wanted to learn, so my instant thought was "Camera!!"